/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.evaluation;

import proguard.classfile.Clazz;
import proguard.classfile.attribute.CodeAttribute;
import proguard.evaluation.value.InstructionOffsetValue;

/**
 * This BranchUnit remembers the branch unit commands that are invoked on it. It doesn't consider conditions when
 * branching.
 *
 * @author Eric Lafortune
 */
public class BasicBranchUnit implements BranchUnit {
    protected InstructionOffsetValue traceBranchTargets;
    protected boolean wasCalled;

    /**
     * Resets the accumulated branch targets and the flag that tells whether any of the branch unit methods was called.
     */
    public void reset() {
        traceBranchTargets = InstructionOffsetValue.EMPTY_VALUE;

        wasCalled = false;
    }

    /**
     * Returns whether any of the branch unit methods was called.
     */
    public boolean wasCalled() {
        return wasCalled;
    }

    /**
     * Returns the accumulated branch targets that were passed to the branch unit methods.
     */
    public InstructionOffsetValue getTraceBranchTargets() {
        return traceBranchTargets;
    }

    // Implementations for BranchUnit.

    public void branch(Clazz clazz, CodeAttribute codeAttribute, int offset, int branchTarget) {
        // Override the branch targets.
        traceBranchTargets = new InstructionOffsetValue(branchTarget);

        wasCalled = true;
    }

    public void branchConditionally(Clazz clazz, CodeAttribute codeAttribute, int offset, int branchTarget,
        int conditional) {
        // Accumulate the branch targets.
        traceBranchTargets = traceBranchTargets.add(branchTarget);

        wasCalled = true;
    }

    public void returnFromMethod() {
        // Stop processing this block.
        traceBranchTargets = InstructionOffsetValue.EMPTY_VALUE;

        wasCalled = true;
    }

    public void throwException() {
        // Stop processing this block.
        traceBranchTargets = InstructionOffsetValue.EMPTY_VALUE;

        wasCalled = true;
    }
}
